1. Field of the Invention
This invention relates to a camera and to a method of controlling the operation thereof.
2. Description of the Related Art
There is a digital camera equipped with a device having both optical and electronic finders (Patent Document 1). The fine optical image of a subject can be seen by using the optical finder, and the image of a subject identical with the captured image of the subject can be seen by using the electronic finder.
Further, there is a camera in which a partial image clipped from a subordinate image obtained from the image sensor of a subordinate imaging unit is superimposed upon a main image obtained from the image sensor of a main imaging unit (Patent Document 2), as well as a camera in which the operation of a conventional image coincidence optical rangefinder is performed by superimposing images from two image sensing devices (Patent Document 3). Furthermore, as examples of cameras concerned with camera shake, there is a camera which, if the amount of camera shake is great, will not enlarge a face area but which, if the amount of camera shake is small, will superimpose an enlarged image of the face area upon the entire image (Patent Document 4), and a camera adapted so as to darken the image of a subject by a polarization filter or the like so that the user will not be aware of camera shake (Patent Document 5).
Patent Document 1: Japanese Patent Application Laid-Open No. 2012-65294
Patent Document 2: Japanese Patent Application Laid-Open No. 2011-135490
Patent Document 3: Japanese Patent Application Laid-Open No. 2007-163724
Patent Document 4: Japanese Patent Application Laid-Open No. 2009-177345
Patent Document 5: Japanese Patent Application Laid-Open No. 2000-258834
Cameras heretofore referred to as high-performance cameras are equipped with a double-image coincidence rangefinder which, when the user performs focusing while looking at the finder device, is such that the image of the subject becomes a pair of offset images if the image of the subject is out of focus, although such offset vanishes when the image of the subject is brought into focus. Hence there is a need to arrange it so that the double-image coincidence system can be applied also to a camera having both the optical and electronic finders mentioned above. However, none of Patent Documents 1 to 3 give any consideration whatsoever to the application of the double-image coincidence system to such an optical/electronic viewfinder. Furthermore, in a case where such double-image coincidence system is considered, not only does the user experience a sense of discomfort when a subject or the camera is in motion but also a problem arises in that there are instances where the user cannot confirm accurate focusing at such time.